1. Technical Field
The present invention relates to a method for determining touch points on a touch panel and a system thereof, and more particularly, to the method for determining one or more touch points on a touch panel and a system thereof.
2. Description of Related Art
Touch panels that allow a user to operate the panels through direct touch operations have been widely accepted in the market because of their humanized operational interfaces. Over the last years, the touch panel technologies have experienced a continuous and rapid development and the prospect thereof is even more promising. Recently, with appearance of iPADs in the market and widespread use of Window 7, the touch panels have almost become a basic configuration of modern information products.
Currently, mainstream touch panel products found in the market are mainly categorized into the resistive ones and the capacitive ones. A resistive touch panel is formed by an indium tin oxide (ITO) glass layer and an ITO film stacked on each other, and requires application of an external force to have the ITO film and the ITO glass layer make contact with each other so that a position of a touch point can be determined through further calculation and processing. However, the resistive touch panel is disadvantageous in that, after an extended time period of use, scratches due to pressing by external forces is liable to occur on the surface of the touch panel to shorten the service life of the touch panel.
On the other hand, a capacitive touch panel operates on the following principle: before the touch panel is touched, all points on the panel are at the same potential level, but once the panel is touched by a user, a weak current will be generated between the user's body and the touch panel to form a capacitive field; then through analysis, a position of the touch point can be determined by the sensors. Furthermore, when the user slides his finger on the touch panel, a touch path of the user can be depicted.
However, the capacitive touch panel is mainly disadvantageous in that, it is very sensitive to the ambient conditions, so any variation of the ambient temperature, the moisture or the ambient electric fields will cause a signal drift or generation of noises to the capacitive touch panel, which has a direct influence on accuracy of the touch panel.
Additionally, the projective capacitive touch panel, which is a kind of further improved capacitive touch panel, has a multi-touch function; i.e., more than one touch point can be detected on the touch panel. Unfortunately, for such a touch panel that supports the multi-touch function, a problem of ghost points tends to occur in determining positions of touch points.
FIG. 1 is a schematic view illustrating formation of ghost points in the prior art. As shown in FIG. 1, the prior art touch panel that supports the multi-touch function utilizes two sensing boards to sense a longitudinal coordinate and a horizontal coordinate, respectively. Hence, when a user touches the touch panel with two fingers, the two touch points will induce two wave crests in the longitudinal direction and the lateral direction respectively. Then through an intersection calculation, this results in four touch points, two of which are the real touch points 101, 102 and the remaining two of which are false touch points 103, 104 (i.e., the so-called ghost points) that tend to cause false determination of the system. Even further, in case of a three-point touch, six false touch points will be derived, which means that the greater the number of the touch points is, the more serious the false determination caused by the ghost points will be.